FLAT PANEL DISPLAYS WITH PRIMARY VIEWING ENVELOPES AWAY FROM DISPLYAY PANEL NORMAL

摘要

We disclose a flat panel display suitable for viewing primarily from viewing angles or envelopes that are away from the direction that is perpendicular to the display panel (display normal). We disclose a way of increase the brightness of the display at large viewing angles. It is desirable to have such a display when the display is primarily viewed from directions that are not along the display normal, such as in the case of the cockpit of a transport aircraft where a display could be viewed mostly from left and right by the pilot and co-pilot. The display uses a light re-distributor (LRD) to increase the brightness of the display at larger viewing angles. The LRD consists of light re-directing portion, light straight-transmission portion and light scattering portion. For transmissive or transflective displays, light rays from the backlight entering the LRD at the light-redirecting portions are redirected and the rays that hits the light straight-transmission portion pass the LRD without changing direction. The surface profile of the light-redirecting portion determined the viewing angles/envelopes at which the light is directed to. This surface profile and the ratio of the light-redirecting portion to the light straight-transmission portion determine how much light is redirected to the viewing angles. The light distribution can be further modified by introducing a diffuser, either by surface treatment or by laminating a diffuser film onto the LRD. The diffuser can be used to smooth out brightness sharp changes at the boundaries of primary and secondary viewing envelopes. Commercially available materials, light-redirecting films and diffuser films can be used to construct a LRD of desired light re-distributing properties, making the LRD a cost effective element of the display. The LRD can be used for displays other than LCD, such as light emitting displays where no backlight exists, by placing the LRD on top the front substrate of the display.